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Accordingto clinical symptoms, attention deficit and hyperactivity disorder (ADHD) iscategorized into three groups: the predominantly inattentive subtype (ADHD-I),the predominantly hyperactive-impulsive subtype (ADHD-HI), and the combinedsubtype (ADHD-C). Recent advances in neuroimaging have demonstrated newapproaches for assessing the ADHD subtypes with underlying pathophysiology.This study aims to examine the hemodynamic response and reaction time (RT) inhealthy children and the ADHD subtypes as measured by functional near-infraredspectroscopy (fNIRS) during an auditory oddball attention task. The sample wasmade up of 40 children divided into four groups: control group (n=14), ADHD-Igroup (n=9), ADHD-HI group (n=6), and ADHD-C group (n=11). The target responseswere identified and were grand-averaged for each participant. Right prefrontalcortex hemodynamic responses and groups performances on RT were comparedbetween subtypes and between controls and subtypes. Functional near-infraredspectroscopy indicated that while control subjects exhibited higher activationthan all ADHD subtypes, the ADHD subtypes did not differ from one another.Relative to control subjects, a longer RT was observed in all ADHD subtypes.The ADHD-I group showed significantly longer RTs compared to the ADHD-HI andADHD-C groups. This study can bring a new perspective to the continuingcontroversy about ADHD subtypes, and the findings may help in the evaluation offNIRS, RT, and RT variability studies in ADHD.